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# About

About

Different options are available in the options table. They are display options, calculations options or add-ins for input data.

For more details, see the related tutorial.

Mode

This option applies to optimization and for "spot diagram", "ray aberration", "encircled energy", "WFE", "PSF", "PSF CROSS" and "MTF" calculations.

If the option "at finite distance" is selected, the surface of analysis is the "analysis surface" (detailed below) otherwise the, the analysis surface s considered at infinity and the calculations are processed in the angular space.

Wavelength

The wavelength cell enables to select either one of the active wavelengths or all the active wavelengths defined in the "wavelengths" input page.
This option is used differently depending on the calculation... (see options table tutorial)

Field

This option enables to select either one of the active field or all the active fields defined in the fields input table. It is suitable for "aberrations" calculations only and is used differently depending on the calculation

"2D ray tracing", "3D texture ray tracing", "3D wireframe ray tracing", "spot diagram", "ray aberration", "encircled energy", "MTF" and "vignetting"

If only one activated field is selected, the calculation is realized for this field only otherwise it is realized for all the activated fields... (see options table tutorial)

Display plan

This option applies only to "2D ray tracing" and "paraxial conjugation" calculations. It defines the display plane which can be either XZ or YZ.

First surface

This option applies only for the "2D ray tracing", "3D wire frame ray tracing" and "3D texture ray tracing". The selected surface is the first surface to be displayed. Therefore no rays nor surfaces prior to this said first surface are displayed.

Last surface

This option applies to all calculations except to "paraxial/aperture" calculation. If "obs" is selected, the system is fully considered and the surface of analysis, if any, is the observation surface. If another surface identifier (for instance the identifier "k") is selected, the system is truncated. It is considered up to the surface "k" which becomes the "new" observation surface and therefore the surface of analysis if any.

Reference

This option applies to "spot diagram" and "encircled energy". For each considered field, it defines the center of the spot diagram from which are calculated the distances to the rays impacts enabling to define the various spot diameters (geometric and RMS) as well as the encircled energies. The reference can be either "chief ray" or "centroid". If "chief ray" is selected, the reference is the intersection of the chief ray with the observation surface. If "centroid" is selected, the reference is the center of gravity of all rays impact on the observation surface ponderated with the weights of the selected activated wavelengths. For the "spot diagram" calculation, the reference is also the center of the Airy disk.

Rays density

This option applies to "2D ray tracing", "3D wire frame ray tracing", "3D texture ray tracing", "spot diagram", "vignetting" and "transmission". The number of rays to be launched increases with the specified "ray density" up to a maximum value considered too high for the server capabilities. This maximum is not fixed. It depends on other parameters, in particular the number of wavelengths, the number of fields and obviously the selected calculation. For all other calculations than those mentionned above, the rays density is fixed by the software.

Airy disk

This option applies to "spot diagram" calculation only. The Airy disk is calculated and displayed for all considered fields only if "yes" is selected. The Airy disk is centered on the reference (see Reference section above). Its diameter is calculated according to the Wavelength section above.

Type of fan

This option applies to "ray aberration" calculation only. It defines the different projection planes for the ray aberration calculation and display. The rays are launched in the tangential plane and in the sagittal plane. The ray aberrations can be projected on the X, Y, tangential, sagittal axis. More details are provided in the "ray aberration" tutorial.

Type of encircled energy

This option applies obviously to the "encircled energy" calculation. If "circular limit" is selected, the curve(s) represent(s) the energy concentrated in a circle centered on the reference (see Reference section above) and which radius is represented as the abscissa. If "x edge limit" or "y edge limit" are selected, the curve(s) represent(s) the energy concentrated respectively in a band along Y axis or X axis, centered on the reference, and which half thickness is represented as the abscissa.

PSF cut-out axis

This option applies obviously to the "PSF cut out" calculation. The PSF cut out is displayed along X axis or Y axis depending if X axis or Y axis is selected. In all cases, the "PSF cut out" is displayed from the "PSF" matrix which lines are in line with X axis and columns are in line with Y axis. The maximum of the PSF matrix is first calculated and the "PSF cut out" is the line or the column of the PSF matrix containing this maximum.

Object X

This option applies to "one ray calculation" and defines the X coordinate of the point on the object surface from which the ray is launched. If the object is at infinity, Object X is the angle between Z and the projection of the ray on the XZ plane. It is then expressed in degrees.

Object Y

This option applies to "one ray calculation" and defines the Y coordinate of the point on the object surface from which the ray is launched. If the object is at infinity, Object Y is the angle between Z and the projection of the ray on the YZ plane. It is then expressed in degrees.

norm. X on pupil

This option applies to "one ray calculation" and defines the normalized coordinate of incident the ray on the aperture in the object space along the X axis. "-1" and "1" values correspond to rays impacting the edge of the aperture along the X axis. Note that if norm. X on pupil is used in the calculation, nor Dir. cosine X, neither Dir. cosine Y are considered.

norm. Y on pupil

This option applies to "one ray calculation" and defines the normalized coordinate of the incident ray on the aperture in the object space along the Y axis. "-1" and "1" values correspond to rays impacting the edge of the aperture along the Y axis. Note that if norm. Y on pupil is used in the calculation, nor Dir. cosine X, neither Dir. cosine Y are considered.

Dir. cosine X

This option applies to "one ray calculation" and defines the director cosine on the X axis of the incident ray. It is defined in the coordinate system of the object surface. Note that if Dir. cosine X is used in the calculation, nor norm. X, neither norm. Y are considered. Note that this cell is not considered if the object is at infinity (see "ray direction" section below).

Dir. cosine Y

This option applies to "one ray calculation" and defines the director cosine on the Y axis of the incident ray in the object space. It is defined in the coordinate system of the object surface. Note that if Dir. cosine Y is used in the calculation, nor norm. X, neither norm. Y are considered. Note that this cell is not considered if the object is at infinity (see "ray direction" section below).

ray direction

This option applies to "one ray calculation" and specifies how the incident ray direction is defined. The direction is defined by "norm. X on pupil" and "norm. Y on pupil" if "with pupil coord." is selected (see section norm. X on pupil and norm. Y on pupil above ). It is defined by the coordinates "Dir. cosine X" and "Dir. cosine Y" of the ray if "with dir. cosine" is selected (see section Dir. cosine X and Dir. cosine Y above ). Note that "with dir. cosine" can not be selected if the object is at infinity as the direction the incident ray is then defined by "Object X" and "Object Y".

rotation X

This option applies to "3D wire frame ray tracing" and "3D texture ray tracing". it defines the rotation angle of the system around the X axis for the default view. (see also the the section "rotation order" below and the "surface parameters" input page tutorials).

rotation Y

This option applies to "3D wire frame ray tracing" and "3D texture ray tracing". it defines the rotation angle of the system around the Y axis for the default view. (see also the the section "rotation order" below and the "surface parameters" input page tutorials).

rotation Z

This option applies to "3D wire frame ray tracing" and "3D texture ray tracing". it defines the rotation angle of the system around the Z axis for the default view. (see also the the section "rotation order" below and the "surface parameters" input page tutorials).

rotation order

This option applies to "3D wire frame ray tracing" and "3D texture ray tracing". It defines the order of the different rotations around the different axis to be applied to the system for the default view. Note that each rotation applies to the coordinate system obtained from the precedent rotation and note the initial coordinate system (see also the "surface parameters" input page tutorials).

vignetting

This option applies to "2D ray tracing" only. Only the rays transmitted by the system are displayed if no vignetting rays is selected. Vignetted rays are also displayed if vignetting rays is selected.

links

This option applies to "2D ray tracing", "Wireframe ray tracing" and "3D texture ray tracing". It manages how the surfaces are joined together. If "automatic" is selected, adjacent surfaces encompassing material different than air or vacuum are automatically joined together except if one of the surface is a mirror. If "manual" is selected, the user can manually select which surface is joined to the preceding one in the "links and obturation" table displayed through the "surface parameters" link.